The proposed research will evaluate the genetic risk involved in human embryo transfer by determining cytogenetically the chromosome aberrations specific of in vitro fertilization products. BIBLIOGRAPHIC REFERENCES: P. Soupart and P. A. Strong. Ultrastructural Observations on Polyspermic Penetration of Zona Pellucida-free Human Oocytes Inseminated In Vitro. Fertil. Steril. 26: 523-537, 1975. P. Soupart. Fecundacion Humana Experimental. Sexualmedica, #13, Febrero, 9-31 and 70-74, 1975.